[nourishingvoid]

Anyone who lives in Japan can register a legal alias, regardless of their citizenship. The special permanent residents that you mentioned (who typically hold North / South Korean or Chinese citizenship) are probably the most common users, but some Japanese people who are divorced use them, too.

An alias with Kanji is really useful for living in Japan. I'm an American citizen but I use an alias with a Kanji last name for just about everything I can (including my job, bank account, and apartment contract). Immigration paperwork and credit cards are just about the only things where the alias can't be used.

[seanmcdirmid]

That is actually a crazily innovative solution to a hard problem. I wish China would adopt something like this.